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A bit of delay answering you, but I was inspired by your question to do some research of my own. This is a hard question to answer, obviously, as we will probably never know exactly how much footage has been shot or who still is holding on to private footage (knowingly or unknowingly).

Anyway, I took a baseline off of Aikido Journal's "Founder's Course", on the working assumption that the late Stanley Pranin was already very thorough in releasing everything he could put his hands on (and gain rights to release). In that collection, not including the three audio-only interviews and the documentary compilations, and subtracting Pranin's later additions (introductions, extra fades, etc.), there is about 3:29:30 of original footage, of which Ō-Sensei is on camera for about 2:47:47. Now, it can be a bit of a judgement call for how much footage qualifies as "doing aikido" but my personal assessment gives 2:03:25.

From here on out I'm quoting times as:
(footage as originally assembled/filmed) / (Ō-Sensei time on camera) / (Ō-Sensei "doing aikido")

Aikido Journal's Founder's Course Totals*: 3:29:30 / 2:47:47 / 2:03:25.
(* for the time being, I have excluded the color footage from Honolulu Aikikai Grand Opening 1961, as the camera filming this seems to have been located immediately next to the B&W camera and was otherwise recording the same footage. I have also excluded "instant replay" footage, throughout)

Scrounging the internet outside of Aikido Journal (mostly Youtube), I found a very limited amount of footage that was not already preserved by Aikido Journal. These are:

Now, I found all of two videos that overlap footage from the Aikido Journal Collection, but have a small amount of footage that was edited out at some point. These cover the two rooftop demonstrations at the Japanese Self-Defense Agency HQ in 1957 and 1958. Both are edited in a different order than the Aikido Journal Version.

A Compilation to Accompany Zen Combat by Jay Gluck
This features both 1958 Rooftop Footage and a short excerpt from Lee Green's Rendezvous with Adventure; there is a small amount of "deleted scene" footage in the rooftop section, but the "Rendezvous" footage is directly copied.
0:05:15 / 0:05:10 / 0:05:10; exclusive footage: 0:00:28 / 0:00:28 /0:00:28

GRAND TOTALS: 3:58:33 / 3:03:17 / 2:16:30

Honorable mention to footage recovered by Jack Wada of Ō-Sensei at Kumano Hongu Shrine in 1967
It seems to be from a single camera at the event, and is quite degraded. It's hard to tell in it's degraded state, but, it appears to have already been included —in it's entirety, and better preserved—in Aikido Journal's presentation of the same event.

植芝盛平合気道の奥義 This is, I believe, from the collection of Arikawa Sadateru (a student of his, whose name I forget, is caretaker of his archives, which were huge).

Also, another 1950's student of the Aikikai, named Iimura (who taught a small class at the Nippon Budokan and who used to circulate around Doshu's class in the 1970's teaching on his own initiative) reportedly had quite a large archive of films of Ueshiba. He did not like non-Japanese at all. I have no idea what has happened to his archive.

Thanks for the DVD recommendation! I was able to find (and order) the series on Budovideos.com, which has an English language interface (I still have a long ways to go on my Japanese studies).

If you ever get bored and decide to hop on a ferry to explore Poulsbo (or Kitsap County, in general), might I recommend visiting Sound Brewery's Tasting Room (Belgian style brews and pretty good food). It's our dojo's usual hang out Tuesday-Thursday after evening practice. Our little dojo is also a couple hundred yards away on the opposite side of the street.